public interface IList {
    int size(BinaryTree.BTNode root);
    int getLeafNodeCount(BinaryTree.BTNode root);
    int getKLevelNodeCount(BinaryTree.BTNode root);
    int getHeight(BinaryTree.BTNode root);
    BinaryTree.BTNode find(BinaryTree.BTNode root,int val);
    void levleOrder(BinaryTree.BTNode root);
    boolean isCompleteTree(BinaryTree.BTNode root);
}
